Of the 156 Intended Nationally Determined Contributions (INDCs) submitted to the UNFCCC by the closure of COP 21 and the adoption of the Paris Agreement in December 2015, at least 78% of these INDCs included conditions. In most cases Parties submitted a conditional contribution alongside an unconditional contribution,but approximately one third of INDCs include only a conditional contribution. This briefing paper by NewClimate Institute concisely presents the key information and aspects on the conditionality of countries‘ mitigation contributions in their INDCs. It gives an overview of the variety of forms of conditional contributions and of the types of conditions, which closely reflect some of the important issues discussed at the international policy level. In addition, the paper examines the implications of conditionality for the effort by the international community to address climate change collectively, with particular focus on climate change mitigation ambition levels, procedural and legal implications, as well as the international finance and support streams.